Debug only clears errors if the machine locks up with a system problem. No details .
I think you can de-select hopper but you need a set chip and you need to understand that you have to do a complete setup configuration, once you setup a GameMaker there is no backing up. So be sure to watch or read the posts on how setup works.
BRW the hopper motor never needs to run backwards other than to back out a jammed coin. If it runs forward the motor is doing what it needs to do.